Emilia Lahti, a PhD candidate at Aalto University in Helsinki and former student of Angela Duckworth at University of Pennsylvania, studies the concept of Sisu and how it applies to our lives. According to Lahti, “Sisu is the concept of taking action in the face of significant adversity or challenge. It is not so much about achievement as it is about facing your challenges with valor and determination.” She goes on to say, “Sisu provides the final empowering push, when we would otherwise hesitate to act.” [3]

In many ways, Sisu is similar to grit, which has been shown to be one of the best predictors of success in the real world. For example, Angela Duckworth’s research on grit has shown that…

West Point cadets who scored highest on the Grit Test were 60% more likely to succeed than their peers.

Ivy League undergraduate students who had more grit also had higher GPAs than their peers — even though they had lower SAT scores and weren’t as “smart.”

When comparing two people who are the same age but have different levels of education, grit (and not intelligence) more accurately predicts which one will be better educated.

Competitors in the National Spelling Bee outperform their peers not because of IQ, but because of their grit and commitment to more consistent practice.

But Sisu runs even deeper than grit. It is a type of mental toughness that allows you to bear the burden of your responsibilities, whatever they happen to be, with a will and perseverance that is unbreakable. It is the ability to sustain your action and fight against extreme odds. Sisu extends beyond perseverance. It is what you rely on when you feel like you have nothing left.